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Byju's Answer

Standard XII

Chemistry

Redox Reactions

A certain pal...

Question

A certain pale-green substance $A$ becomes dark brown on adding $N a N O_{2}$ in presence of dilute $H_{2} S O_{4}$ . Its aqueous solution gives precipitates with $B a C l_{2}$ and $N a O H$ in separate tests. The latter precipitate $B$ gradually changes colour from green to brown on exposure to air. What is $A$ ?

N i S O_{4}

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F e S O_{4}

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C u S O_{4}

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C r_{2} {(S O_{4})}_{3}

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Solution

The correct option is B $F e S O_{4}$
$A$ is $F e S O_{4}$ ,
Reactions:
$F e S O_{4} + B a C l_{2} \to B a S O_{4}$
white ppt.
$F e S O_{4} + N a O H \to F e (O H)_{2}$
white ppt.

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Similar questions

Q. Two solid laboratory reagents (A) and (B) gives the following reactions:
Compound (A):
(i) on strongly heating gives two oxides of sulphur
(ii) on adding aqueous NaOH solution to its aqueous solution, a dirty green precipitate is obtained which starts turning brown on exposure to air
Compound (B) :
(iii) imparts green colour to the flame
(iv) Its solution does not give a precipitate on passing

H_{2} S

(v) When it is heated with solid

K_{2} C r_{2} O_{7}

and concentrated

H_{2} S O_{4}

, a red gas is evolved. The gas when passed in an aq NaOH solution turns it yellow
Compound (A) and (B) are identified as

F e S O_{4}

and

B a C l_{2}

.
If true enter 1, else enter 0.

Q. A coloured precipitate is obtained when

H_{2} S

gas is passed through an aqueous solution of a salt in the presence of ammonium hydroxide. The precipitate dissolves in dilute

H C l

and reacts with

N a O H

to give white precipitate which on standing turns into a brown/black mass. The brown/black mass on fusion with

K N O_{3}

and

N a_{2} C O_{3}

gives green mass. The cation of the salt is:

Identify the substances based on the information given below and choose the correct option:

The pale green solid R turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.

Q. A light bluish green crystalline compound responds to the following tests:
(i) Its aqueous solution gives a brown precipitate or colouration with alkaline

K_{2} [{H g I}_{4}]

solution.
(ii) Its aqueous solution gives a blue colour with

K_{3} [{F e (C N)}_{6}]

solution.
(iii) Its solution in hydrochloric acid gives a white precipitate with

{B a C l}_{2}

solution. The molecular formula of the compound is

F e S O_{4} . (N H_{4})_{2} S O_{4} . 6 H_{2} O

(Mohr's salt)

If the given statement is true enter 1 else enter 0.

Select the correct answers :

(a) Colour of an aqueous solution of copper sulphate is

(i) Green (ii) Brown (iii) Blue (iv) Yellow

(b) Colour of the precipitate formed on adding $N a O H$ solution to iron (II) sulphate solution is

(i) White (ii) Brown (iii) Green (iv) Pale blue

(i) Iron (ii) Magnesium (iii) Zinc (iv) Copper

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A certain pale-green substance A becomes dark brown on adding NaNO2 in presence of dilute H2SO4. Its aqueous solution gives precipitates with BaCl2 and NaOH in separate tests. The latter precipitate B gradually changes colour from green to brown on exposure to air. What is A?

The correct option is B FeSO4A is FeSO4,Reactions:FeSO4+BaCl2→BaSO4 white ppt.FeSO4+NaOH→Fe(OH)2 white ppt.

The correct option is B $F e S O_{4}$
$A$ is $F e S O_{4}$ ,
Reactions:
$F e S O_{4} + B a C l_{2} \to B a S O_{4}$
white ppt.
$F e S O_{4} + N a O H \to F e (O H)_{2}$
white ppt.